Rotary pumps, compressors or motors



Oct. 4, 1966 F. w. M COMBIE ROTARY PUMPS, COMPRESSORS OR MOTORS Filed Nov. 30, 1964 INVENTOR' FREDERicK g4 mcoMBiE y KW ATTORNEYS United States Patent "ice 3,276,391 ROTARY PUMPS, COMPRESSORS 0R MOTORS Frederick Walter McCombie, London, England, assignor t0 Megator Pumps and Compressors Limited, London, England, a British company Fiied Nov. 30, 1964, Ser. No. 414,681 Claims priority, application Great Britain, Dec. 12, 1963, 49,150/ 63 5 Claims. (Cl. 103-202) The present invention is concerned with the construction of shoes of the kind included in rotary pumps, compressors or motors of the type forming the subject of my prior US. Patents Nos. 2,814,256, 2,561,808, 2,612,846, 2,561,809 and 2,561,810. Such shoes are recessed for the entry of an eccentric disc on an associated shaft, the recess constituting in conjunction with the eccentric, a displacement chamber of variable volume, each shoe being formed with discharge ports and inlet ports in one flat face which co-operate with discharge ports and inlet ports in a port plate with which the shoe engages under the pressure of the working fluid and over which plate the shoe moves with a to and fro reciprocating movement, as a result of rotation of the shaft and associated eccentric.

It is a feature of such pumps, compressors or motors that the shoes are constructed so as to be deformable under hydraulic pressure into intimate contact with their associated eccentrics. It is undesirable, however, for the face of the shoe which engages the port plate to be composed of a material which will deform under internal hydraulic pressure as there is considerable risk of the material comprising the shoe being worn or damaged by being extruded into the ports of the port plate as the shoe moves to and fro to cover and uncover the ports.

To avoid such extrusion of the shoe material it has been the practice to form the port plate engaging face or base from a harder material than the main body of the shoe and to secure the parts together in various Ways, for example by moulding the shoe body onto the base.

A shoe in accordance with the present invention includes a body and base, the base being composed of a harder material than the body and although it is preferred in carrying the present invention into practice to mould the body onto the base, it is nevertheless within the scope of the invention to produce the components as two separate mouldings which are subsequently bonded together by means of a suitable adhesive.

It will be appreciated that if the shoe body is moulded onto the harder base, the shoe body being composed of natural or synthetic rubber or other elastomeric material, it is essential that there shall be virtually no obstruction to the entry of the material into the mould to ensure that the moulding is homogeneous and that the body and base are virtually permanently united together without distortion of either part.

A shoe in accordance with the present invention comprises a shoe body and a base composed of suitable materials the base being of a harder material than the body, the base comprising a ported flat faced component for slidably engaging the port plate and having a pair of laterally spaced side portions which in the finished shoe lie flush with the sides of the shoe body.

The base which is preferably formed by a moulding operation is in the preferred method placed in the mould designed to receive the shoe body forming material, with the outer faces of the two side portions in close contact with the adjacent surfaces of the mould, the shoe body forming material being then introduced. The body forming material will not be liable to find its way between the side portions of the base and the mould sides which might result in distortion of the sides of the base, as the Patented Oct. 4, 1966 side portions are in close contact with the side of the mould whilst the side portions will offer virtually no obstruction to the entry of the shoe body forming material. When the mould is filled under pressure the outward pressure on the side portions will be taken by the mould sides and consequently there will be no appreciable outward deflection of the side portions.

Referring to the accompanying drawings:

FIGURE 1 is a section of a rotary pump fitted with the type of shoe forming the subject of the present invention;

FIGURE 2 is a vertical section of a shoe in accordance with the invention;

FIGURE 3 is a plan view;

FIGURE 4 is an inverted plan view; and

FIGURE 5 is a section on the line A-B in FIGURE 2.

Referring in the first case to FIGURE 1 of the drawings, the rotary pump illustrated includes a casing 1 fitted with a port plate 2 formed with ports for the entry and discharge of fluid into and out of a shoe 3 which is maintained in contact with the port plate by the pressure of fluid in the pump casing and is reciprocated over the surface of the port plate by an eccentric 4 fitting the shoe, to open and close the ports in the port plate and thus control the flow of fluid therethrough, the shoe in conjunction with the eccentric constituting a displacement chamber. Such a pump forms the subject of one or other of the earlier patents above referred to.

The improved shoe shown in FIGURES 2 to 5, includes a body 5 and a base 6 generally of channel shape in cross-section. The base 6 is composed of a harder material than the body 5 for the purpose hereinbefore referred to.

The base and body are formed with a pair of substantially rectangular ports 7.

The edges 9 of the side portions or flanges of the base are preferably double-bevelled so as to form an inverted V shape as shown in FIGURE 5. This construction has two main advantages. First, the elastomeric body-forming material along the outer slope of the V on each flange forms a lip which, under the hydrostatic pressure in the casing of the pump, makes a tight seal, resisting any tendency for liquid under pressure to force open or seep along the joints between the two portions of the shoe. Secondly, the inner slope of each V assists the free flow of the body forming material and the complete filling of the mould during the moulding operation.

The side portions of the channel shaped base preferably taper slightly in an upward direction to facilitate production of the base by moulding and to assist in the complete filling of the mould when moulding the body onto the base.

The shoe body may be composed of a natural or synthetic rubber or other suitable elastomeric material whilst the base is composed of a harder and more rigid material. The base, for example, may be composed of a thermo-setting synthetic resin composition or alternatively a thermo-plastic synthetic composition which will not be liable to distort at a temperature such as is likely to be reached during curing of the shoe material if necessary.

Alternatively the base may be principally composed of one material, selected for example for its strength, but with the port plate engaging face made of another material selected for its wear-resisting properties, the former material being bonded or moulded on to the latter.

Although generally the engaging faces of the body and base will be flat or substantially flat the faces may be specially shaped so that they interlock as for example by forming the faces with interengagin-g projections and recesses.

It will be appreciated that the proposed shoe when completed will be capable of inward deflection over that area engaged by the eccentric and that the opposite end of the shoe where it engages the port plate and also the sides of the shoe near the port plate will be comparatively rigid and unyielding to fluid pressure.

I claim:

1. A shoe, or displacement chamber, for use with an eccentric rotor of a rotary machine, such as a rotor pump or compressor, comprising a body defining a chamber having side and end Walls and a bottom wall but open at its upper end to guidingly receive an eccentric rotor within its interior for reciprocating the body, a base having a bottom wall and side walls defining a channel in cross section, said body being seated in the channel of the base whose side walls embrace the side walls of the body, and aligned ports in said base and body communicating the under side of the bottom wall of the base with the interior of said body, said base being of a material Which is relatively harder than that of the body and being bonded to said body along said channel surfaces, whereby said body is deformable under hydraulic pressure into intimate contact With an associated eccentric rotor while said base is not deformable thus preventing wear or damage as the base reciprocates over a port plate.

2. A shoe according to claim 1 wherein said base is pre-moulded and said body is moulded onto said base.

3. A shoe as claimed in claim 1, wherein the base and body are of identical width, the outer surfaces of the side Walls of the base lying flush with the outer surfaces of the side walls of said body.

4. A shoe as claimed in claim 3, wherein the upper edges of the side walls of the channel shaped base are of substantially inverted V shaped in cross-section.

5. A shoe as claimed in claim 3, wherein the side walls of the channel shaped base taper in thickness towards their upper edges.

References Cited by the Examiner UNITED STATES PATENTS 844,307 2/1907 Harmer 251-326 X 2,750,896 6/1956 McCombie 103l63 X FOREIGN PATENTS 16,896 1914 Great Britain.

ROBERT M. WALKER, Primary Examiner. 

1. A SHOE, OR DISPLACEMENT CHAMBER, FOR USE WITH AN ECCENTRIC ROTOR OF ROTARY MACHINE, SUCH AS A ROTOR PUMP OR COMPRESSOR, COMPRISING A BODY DEFINING A CHAMBER HAVING SIDE AND END WALLS AND A BOTTOM WALL BUT OPEN AT ITS UPPER END TO GUIDINGLY RECEIVE AN ECCENTRIC ROTOR WITHIN IT INTERIOR FOR RECIPROCATING THE BODY, A BASE HAVING A BOTTOM WALL AND SIDE WALLS DEFINING A CHANNEL IN CROSS SECTION, SAID BODY BEING SEATED IN THE CHANNEL OF THE BASE WHOSE SIDE WALLS EMBRACE THE SIDE WALLS OF THE BASE BODY, AND ALIGNED PORTS IN SAID BASE AND BODY COMMUNICATING THE UNDER SIDE OF THE BOTTOM WALL OF THE BASE WITH THE INTERIOR OF SAID BODY, SAID BASE BEING OF A MATERIAL WHICH IS RELATIVELY HARDER THAN THAT OF THE BODY AND BEING BONDED TO SAID BODY ALONG SAID CHANNEL SURFACES, WHEREBY SAID BODY IS DEFORMABLE UNDER HYDRAULIC PRESSURE INTO INTIMATE CONTACT WITH AN ASSOCIATED ECCENTRIC ROTOR WHILE SAID BASE IS NOT DEFORMABLE THUS PREVENTING WEAR OR DAMAGE AS THE BASE RECIPROCATES OVER A PORT PLATE. 